1. Field of the Invention
The invention relates in general to a monitoring circuit, a monitoring device, and a monitoring method thereof, and more particularly to a monitoring circuit for monitoring whether a wafer is loaded or unloaded abnormally, a monitoring device for monitoring an abnormal load or unload operation of the wafer, and a monitoring method thereof.
2. Description of the Related Art
In the semiconductor manufacturing processes, a wafer is important for manufacturing semiconductor devices. The wafer is usually carried by a carrier. When the wafer is being processed, a manipulator unloads the wafer from the carrier, and transfers the wafer to a chamber for further processing. Thereafter, the manipulator loads the processed wafer to the carrier so as to complete the load and unload operation of the wafer.
When the manipulator loads or unloads the wafer, if the position of the wafer in the carrier is deviated from its proper position, the manipulator may fail in normally loading or unloading the wafer. Moreover, the wafer may be damaged undesirably. Thus, it is an important subject to prevent the wafer from being damaged when the wafer is loaded or unloaded.